JP3218852B2 - Power steering system using variable displacement pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to
A variable displacement pump having an eccentricity control mechanism that reduces the pressure acting on the eccentricity control unit using the relative displacement of the cam ring with respect to the rotor to reduce the eccentricity and reduce the discharge flow rate. The present invention relates to a power steering device used.

[0002]

2. Description of the Related Art A conventional power steering device (JP-A-53-13 / 1979)
0504) controls the position of the cam ring R using the differential pressure across the orifice T provided in the discharge oil passage O of the variable displacement pump P as shown in FIG. 9 to control the amount of eccentricity with the rotor RT. Thus, as shown in FIG. 9, even when the rotation speed of the rotor RT increases, the discharge flow rate is kept substantially constant, and an energy saving effect is obtained.

[0003]

In the conventional power steering apparatus, as shown in FIG. 10, when the rotation speed of the rotor RT increases, the discharge flow rate is maintained at a substantially constant value in consideration of steering. Since the flow rate is not reduced even at the time of high rotation, there is a problem that the steering force of the steering wheel becomes light and the operability is reduced at the time of high-speed running.

Therefore, the present inventors have focused on the technical idea of the present invention that the eccentricity is reduced by using the relative displacement of the cam ring with respect to the rotor to reduce the discharge flow rate at the time of high rotation. Furthermore, as a result of repeated research and development, the present invention has been achieved in which the steering force of the steering wheel during high-speed running is prevented from becoming light, and the object of improving operability is achieved.

[0005]

A power steering apparatus using a variable displacement pump according to the present invention (first invention according to claim 1) is provided before and after a first orifice provided in an oil passage to a gear box. In a power steering device using a variable displacement pump capable of controlling the amount of eccentricity between the rotor and the cam ring in accordance with the pressure difference to maintain a constant discharge flow rate regardless of an increase in the number of rotations, A first throttle opened by a relative displacement of the cam ring with respect to the rotor,
To communicate the downstream side of the first orifice with the tank
An eccentricity control mechanism for further reducing the eccentricity by reducing the pressure on the downstream side of the first orifice is further provided.

In a power steering apparatus using a variable displacement pump according to the present invention (a second invention according to a second aspect), in the first invention, the eccentric amount control mechanism has a first spring interposed. One end communicates with the oil passage between the gearbox and the first orifice, and the other end communicates with the cam ring, while the other end communicates with the discharge port of the variable displacement pump. A capacity control valve comprising a mechanically connected spool and a first throttle that reduces the amount of eccentricity by reducing the pressure at the one end by connecting the one end to a tank when the spool reaches a set position. Is what it is.

The power steering apparatus using the variable displacement pump according to the present invention (third invention according to claim 3) is different from the second invention in that a load acting on the gear box introduced at one end is provided. An opening determined by a balance between the pressure, the pressure of the pressure oil supplied to the other end from the first throttle of the displacement control valve, and the biasing force of the second spring inserted at the other end is formed. Second
A bypass control valve having a throttle is added.

[0008] The power steering apparatus using the variable displacement pump according to the present invention (the fourth invention according to the fourth invention) is different from the third invention in that the load acting on the gearbox introduced at one end is different from that of the third invention. When the pressure is smaller than the biasing force of a third spring inserted at the other end, the valve is opened, and a load pressure sensitive valve having a third throttle for supplying the pressure oil at one end of the capacity control valve to the tank is added. It was done.

[0009]

According to the first aspect of the present invention, there is provided a power steering apparatus comprising:
The cam ring is opened by a relative displacement of the cam ring with respect to the rotor at the time of high rotation by the eccentric amount control mechanism.
The downstream side of the first orifice is blocked via a first throttle.
The first orifice.
The pressure on the flow side is reduced to further reduce the amount of eccentricity.

[0010] In the power steering apparatus according to the second aspect of the present invention, the one end in which the first spring is inserted is connected to the gear box, and the other end is connected to a discharge port of the variable displacement pump. In the valve body of the displacement control valve, when the spool mechanically connected to the cam ring reaches a set position during high rotation, the first throttle reduces the pressure by communicating the one end to the tank. By doing so, the amount of eccentricity is reduced.

The power steering apparatus according to a third aspect of the present invention has the above-mentioned structure. In the power steering apparatus according to the second aspect of the invention, in the bypass control valve, the load pressure acting on the gearbox introduced into the one end and the load pressure acting on the gearbox are determined. The degree of opening of the second throttle is adjusted by the balance between the pressure of the pressure oil supplied from the first throttle to the other end of the capacity control valve and the biasing force of the second spring inserted at the other end. Is determined, the second
The amount of pressure oil leaking to the tank via the throttle is controlled based on the pressure of the pressure oil determined by the opening of the first throttle of the capacity control valve.

In the power steering apparatus according to a fourth aspect of the present invention, in addition to the operation of the third aspect, in the load pressure sensitive valve, the load pressure acting on the gear box introduced into the one end of the power steering apparatus is different. When the biasing force of the third spring inserted at the end is smaller, the pressure oil at the one end of the capacity control valve is supplied to the tank through the third throttle, and the one end of the capacity control valve is supplied to the tank. Is reduced.

[0013]

According to the first aspect of the present invention, the opening of the power steering apparatus according to the first aspect of the present invention is caused by the relative displacement of the cam ring with respect to the rotor by the eccentricity control mechanism during high rotation.
Downstream of the first orifice through a first throttle
The first orifice is connected to the
Since the pressure on the downstream side of the wheel is reduced to further reduce the amount of eccentricity, the steering force of the steering wheel at the time of high-speed running is prevented from being reduced, and the operability is improved.

According to a second aspect of the present invention, in addition to the effects of the first aspect, the power steering apparatus according to the second aspect of the present invention is configured such that when the spool for mechanically driving the cam ring is rotated at a high speed in the valve body of the displacement control valve. When the first restrictor reaches the set position, the first throttle communicates the one end to the tank to reduce the eccentricity by reducing the pressure, so that high rotation detection and eccentricity control are performed by the same mechanism. The effect is that the mechanism is simplified, the cost is reduced, and the maintenance is facilitated.

The power steering apparatus according to the third aspect of the present invention having the above-described effects has the same effects as the second aspect of the invention, and the bypass control valve is connected to the first throttle of the load pressure and the capacity control valve. The amount of pressure oil leaking into the tank via the second throttle, the opening of which is determined by the balance between the pressure of the supplied pressure oil and the urging force of the second spring, is determined by the displacement of the displacement control valve. Since the control is performed based on the pressure of the pressure oil determined by the opening degree of the first throttle, the effect of enabling the pressure compensation is achieved.

The power steering apparatus according to a fourth aspect of the present invention having the above-described effects, in addition to the effects of the third aspect, has a function of responding to the load pressure when the load pressure acting on the gearbox is low, such as during non-steering. The valve supplies pressure oil at one end of the displacement control valve to the tank to reduce the pressure, thereby reducing the amount of eccentricity of the variable displacement pump and decreasing the discharge flow rate, thereby realizing an energy saving effect and reducing fuel consumption. This has the effect of achieving

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) A power steering apparatus using a variable displacement pump according to a first embodiment comprises a variable displacement pump 1 in which the amount of eccentricity of a cam ring 11 is controlled, as shown in FIGS. A first orifice 2 disposed in an oil passage between a discharge port 12 of the variable displacement pump 1 and a gear box (not shown), and a piston 155 mechanically connected to the cam ring 11 at a set position. When you reach the first stop 1
57 is opened and the pressure in the spring chamber 151 is reduced to control the amount of eccentricity of the cam ring 11 to decrease, and the load pressure acting on the gearbox and the capacity control valve 15 A bypass control valve 4 having a second throttle 41 for controlling a flow rate leaking from the capacity control valve 15 to the tank 19 based on the pressure of the pressure oil passing through the first throttle 157, and a spring chamber of the capacity control valve 15 The relief valve 5 is connected to the relief valve 151 and releases pressure oil to the tank 19 when the pressure of the spring chamber 151 becomes higher than a set pressure.

The variable displacement pump 1 is shown in FIGS.
As shown in FIG. 1, a cam ring 11 inserted in a pump case 10 and swinging about one point, and a plurality of vanes 13 inserted in the cam ring 11 in a radial direction, for example, an engine mounted on a vehicle (not shown) ), A suction port 16 for sucking pressure oil from a reservoir 17, a discharge port 12 for discharging pressure oil, and a displacement control valve 15 for swinging the cam ring 11.

The displacement control valve 15 is provided with a cylinder 150 formed in the pump case 10 of the variable displacement pump 1.
And a piston 155 inserted in the cylinder 150
And the cam ring 11 disposed on the piston 155.
A pin 152 locked to a lever 153 fixed to the
The second orifice 154 communicates with the first orifice 2 and also communicates with the suction port 16 of the variable displacement pump 1 so that a spring having a predetermined spring constant is inserted and the left end of the piston 155 in the drawing. Spring chamber 1 acting on
51, and a high-pressure chamber 156 communicating with the discharge port 12 of the variable displacement pump 1 and acting on the right end of the cylinder 150 in the drawing.

The piston 155 is provided with the spring chamber 15.
1 is formed with a substantially T-shaped passage 158 communicating with a horizontal passage portion. The first passage 158 is formed by a positional relationship between a discharge port 159 formed at a predetermined position of the cylinder 150 and a vertical passage portion of the T-shaped passage 158. One stop 157 is formed.

As shown in FIG. 1, the bypass control valve 4 has a second load pressure operation port 42 formed at the left end of the valve body 40 to guide the load pressure acting on the gear box. A second introduction port 43 communicating with the discharge port 159 of the capacity control valve 15 is formed at a lower end, and a second discharge port 44 communicating with the tank 19 is formed at the lower end.

As shown in FIG. 1, the bypass control valve 4 is provided with a second spool 45 having a U-shaped vertical section inserted in the valve body 40 and acting on the left end of the load pressure. A second spring 46 interposed between the valve main body 40 and the second spool 45 for urging the second spool 45 leftward with a predetermined urging force, and a discharge port of the valve main body 40 The load pressure acting on the second load pressure acting port 42 formed at the right end in FIG.
A second throttle 41 that supplies the tank 19 with a leak amount of pressurized oil corresponding to an opening determined by the balance between the pressure of the pressurized oil supplied from the discharge port 159 and the urging force of the second spring 46. Consists of That is, the bypass control valve 4 constitutes a pressure compensating valve that keeps the amount of leak to the tank 19 at a value set by the opening degree of the first throttle 159 of the capacity control valve 15.

In the power steering apparatus of the first embodiment having the above-described structure, the pressure oil of the pressure P0 discharged from the discharge port 12 with the rotation of the rotor 14 of the variable displacement pump 1 driven by the engine is used. The first orifice 2 supplies the gearbox as pressure oil at a pressure P1.

When the engine is running at low speed, FIG.
As shown in FIG.
The position at which the discharge port 159 formed at the bottom is not coincident with the position at which the vertical passage portion of the T-shaped passage 158 of the piston 155 is formed, and
Is closed, the differential pressure across the first orifice 2 and the spring chamber 15 of the displacement control valve 15 are reduced.
The position of the spool is determined only by the balance of the urging force of the first spring.

As the rotation increases, the discharge flow rate of the variable displacement pump 1 increases linearly.
Since the pressure difference before and after is increased, the spring of the spring chamber 151 of the displacement control valve 15 is flexed to move the piston 155 to the left in FIG. Accordingly, a constant flow rate-flow rate characteristic as shown in the area a in FIG. 4 is realized.

When the rotation of the engine increases, the differential pressure across the first orifice 2 further increases, so that the spring of the spring chamber 151 of the displacement control valve 15 is bent to further move the piston 155 to the left in FIG. When the vertical passage portion of the T-shaped passage 158 approaches the position where the discharge port 159 formed in the cylinder 150 is formed, the first throttle 157 starts opening and the spring chamber 15
The first pressurized oil has a T-shaped passage 158 and a first throttle 157.
Through the discharge port 159.

The pressure oil in the spring chamber 151 discharged from the discharge port 159 is introduced into the bypass control valve 4 through the second introduction port 43, and acts on the second load pressure operation port 42. Pressure P1 acting on the gearbox and the pressure P of the pressure oil in the spring chamber 151 introduced from the second introduction port 43.
The pressure of the spring chamber 151 is supplied by supplying the tank 19 with a pressure oil having a leak amount corresponding to the opening degree of the second throttle 41 determined by the balance between the pressure of the spring chamber 151 and the urging force of the second spring 46. The pressure of the oil is reduced.

The discharge port 159 allows the spring chamber 15
When the pressure oil 1 is discharged, the pressure in the spring chamber 151 is reduced, so that the piston 155 is further moved to the left in FIG. 1 to greatly reduce the eccentric amount of the cam ring 11 via the lever 153. Since the flow rate decreases as the rotation speed increases, the rotation speed-flow rate characteristic as shown in a region b in FIG. 4 is realized.

When the rotation of the engine is further increased, the piston 155 is further moved to the left in FIG. 1 so that the center of the discharge port 159 formed in the cylinder 150 and the center of the vertical passage of the T-shaped passage 158 are moved. (The left end position), the first throttle 157 has the maximum opening, so that a larger amount of pressure oil in the spring chamber 151 can be supplied to the T-shaped passage 1.
58 and the first outlet 157 through the discharge port 1
It is discharged from 59.

The discharge port 159 allows the spring chamber 15
When the first pressure oil is discharged at the maximum flow rate, the spring chamber 151 is discharged.
However, since the piston 155 is at the left end position in FIG. 1 and the opening of the first throttle 157 is constant, the bypass control valve 4 adjusts the opening of the second throttle 41 to Since the control is performed in accordance with the pressure of the pressure oil from the discharge port 157, the eccentricity and the discharge flow rate become minimum constant values even when the engine speed increases, and FIG.
This realizes a rotation speed-flow rate characteristic as shown in a middle c region.

The power steering apparatus according to the first embodiment having the above-described operation is mechanically integrated with the cam ring 11 which is relatively moved with respect to the rotor 14 by the displacement control valve 15 at the time of high rotation. Using the displacement of the piston 155, the pressure acting on the spring chamber 151 of the displacement control valve 15, which constitutes the eccentricity control unit, is reduced to further reduce the eccentricity. As compared with the case where the discharge flow rate is reduced, a greater energy saving effect can be realized, and at the same time, the steering force of the steering wheel at the time of high-speed running is prevented from being reduced, and the operability is improved.

In the power steering apparatus of the first embodiment, the piston 155 for mechanically driving the cam ring 11 in the cylinder 150 of the displacement control valve 15 is provided.
When the first throttle 157 reaches the set position at the time of high rotation, the first throttle 157 reduces the amount of eccentricity by reducing the pressure by connecting the spring chamber 151 to the tank 19, so that the eccentric amount is reduced. Since the detection of the occurrence and the reduction control of the amount of eccentricity are performed by the capacity control valve 15, which is the same mechanism, the mechanism is simplified, the cost is reduced, and the maintenance is facilitated.

Further, in the power steering apparatus according to the first embodiment, the bypass control valve 4 determines whether the load pressure, the pressure of the pressure oil supplied from the first throttle 157 of the capacity control valve 15 and the second The amount of pressure oil leaking to the tank 19 through the second throttle 41 whose opening degree is determined by the balance with the urging force of the spring 46 is determined by the capacity control valve 19.
Is controlled based on the pressure of the pressure oil determined by the opening degree of the first throttle 157, so that the pressure can be compensated and the flow rate in the region c in FIG. This has the effect of realizing constant characteristics.

(Second Embodiment) A power steering apparatus using a variable displacement pump according to a second embodiment acts on the gear box as in the case of non-steering with respect to the first embodiment apparatus. When the load pressure is low, the spring chamber 15 of the displacement control valve 15
A pressure-sensitive valve 3 having a third restrictor 31 for reducing the eccentricity of the cam ring 11 by reducing the pressure of the pressure oil 1 is added to the first embodiment based on FIG. 5 and FIG. The differences will be mainly described.

As shown in FIGS. 5 and 6, the load pressure sensitive valve 3 has a first load pressure acting port 32 to which a load pressure acting on the gear box is guided to the left end of the valve body 30. A communication port 33 is formed at the right end and communicates with the tank. The communication port 33 communicates with the first orifice 2 via a second orifice 154 at the upper end. A first introduction port 34 communicating with the spring chamber 151 of the capacity control valve 15 for controlling pressure is formed, and a lower end is communicated with the second introduction port 43 of the bypass control valve 4 communicating with the tank 19. First discharge ports 35 are respectively formed.

As shown in FIGS. 5 and 6, the load pressure sensitive valve 3 is inserted into the valve main body 30 and has a U-shaped vertical spool 36 on which the load pressure is applied. When,
The first spool 36 is interposed between the valve body 30 and the first spool 33 and urges the first spool 36 leftward with an urging force smaller than the load pressure during steering and larger than the load pressure during non-steering. A first spring 37 and a load pressure formed on a portion of the first spool 36 facing the first introduction port 34 and acting on the first load pressure operation port 32.
When the urging force of the spring 37 is lower, the spring chamber 151 is opened.
And a third throttle 31 that establishes a communication relationship between the first introduction port 34 communicating with the first discharge port 35 and the first discharge port 35 communicating with the bypass control valve 4.

In the power steering apparatus of the second embodiment having the above-described structure, in the steering state in which the steering wheel is steered, the load pressure P1 acting on the gearbox is high, so that the load pressure sensitive valve is 3 first load pressure acting port 3
Since the pressure acting on the second spool 2 is greater than the urging force of the first spring 37, the first spool 36 moves rightward as shown in FIG. 6, and the third throttle 31 is closed. The pressure of the pressure oil in the spring chamber 151 of the displacement control valve 15 is maintained at a pressure P2 determined by the load pressure and the second orifice 154.

Accordingly, when the pressure P2 of the spring chamber 151 of the variable displacement pump 1 and the discharge pressure become larger than the urging force of the spring, the piston 155 moves to the left in FIG. 6, and the eccentric amount of the cam ring 11 is reduced. As shown in the first embodiment, the characteristic shown by the solid line in FIG.

In a non-steering state in which the steering wheel is not steered, the load pressure P1 acting on the gearbox and the first load pressure acting port 32 is low, so that the second pressure of the load pressure sensitive valve 3 is reduced. Since the biasing force of the first spring 37 is greater, the first spool 36 is located at the left end as shown in FIG. 5, and the third throttle 31 is open. The pressure oil in the chamber 151 is supplied to the first discharge port 3 through the third throttle 31.
5 to the bypass control valve 4.

In the bypass control valve 4, since the load pressure P1 acting on the gear box and the second load pressure acting port 42 is similarly low,
Since the pressure P3 of the pressure oil supplied from the first discharge port 35 of the load pressure sensitive valve 3 and the urging force of the second spring 46 are larger, as shown in FIG. Is located to the left, the second throttle 41 is open to realize a leak amount corresponding to the opening degree of the third throttle 31 of the load pressure sensitive valve 3, so that the load pressure sensitive valve 3 The capacity control valve 15 supplied via the first throttle 31
Of the spring chamber 151 is supplied to the tank 19 from the second discharge port 44.

Accordingly, since the pressure P2 of the spring chamber 151 of the variable displacement pump 1 is lower than that during the steering, the piston 155 moves to the left in FIG. 6 at a timing (lower rotation speed) earlier than during the steering. And the cam ring 1
Since the amount of eccentricity of 1 is reduced, the characteristic shown by the broken line in FIG. 7 is realized.

The power steering apparatus according to the second embodiment having the above-described operation has the same effects as those of the first embodiment described above.
When the load pressure acting on the gear box falls below a certain value, such as during non-steering, the load pressure sensitive valve 3 is adjusted based on the load pressure at an earlier timing (lower rotation speed) than during steering. Since the discharge flow rate is reduced and made constant by reducing the amount of eccentricity of the displacement pump 1, an energy saving effect is realized and an effect of reducing fuel consumption is achieved.
That is, the power steering apparatus according to the second embodiment achieves an energy saving effect in a low rotation region such as at the time of idling, and has an effect of reducing fuel consumption on a congested road or the like.

(Third Embodiment) A power steering apparatus using a variable displacement pump according to a third embodiment is configured as shown in FIG.
By omitting the bypass control valve 4 of the embodiment, the discharge port 15
9 supplies pressure oil directly to the tank 19 to
By controlling the pressure of No. 1, the eccentricity of the variable displacement pump 1 is controlled, thereby achieving the effect of realizing energy saving and fuel consumption reduction, and further simplifying the configuration as compared with the above-described embodiment to reduce the cost. This has the effect of facilitating maintenance.

The above-described embodiments have been described by way of example only, and the present invention is not limited thereto. Those skilled in the art will recognize from the claims, the detailed description of the invention, and the drawings. Modifications and additions are possible without departing from the technical idea of the present invention.

For example, in the above-described embodiment, an example has been described in which the throttle of the displacement control valve for controlling the amount of eccentricity of the variable displacement pump is formed to detect the position of the cam ring and to control the amount of eccentricity. The invention is not limited to these, and the cam ring is used in a variable displacement pump of the type in which the discharge pressure and the load pressure directly act on the pressure receiving portion of the cam ring by directly detecting the movement of the cam ring itself and controlling the opening and closing of the throttle. It is also possible to adopt a mode in which the load pressure acting on the pressure is reduced.

In the above-described second embodiment, the example in which the load pressure sensitive valve and the bypass control valve are separately provided has been described. However, the present invention is not limited to these, and the aspect in which the bypass control valve is omitted is provided. Can also be adopted.

[Brief description of the drawings]

FIG. 1 is a hydraulic system diagram of a first embodiment of the present invention at the time of high rotation.

FIG. 2 is a hydraulic system diagram of the first embodiment at a low rotation speed.

FIG. 3 is a sectional view showing a variable displacement pump of the first embodiment.

FIG. 4 is a diagram showing a rotation speed-flow rate characteristic of the variable displacement pump of the first embodiment.

FIG. 5 is a hydraulic system diagram of the device of the second embodiment at the time of high rotation and high pressure.

FIG. 6 is a hydraulic system diagram of the device of the second embodiment at low rotation and low pressure.

FIG. 7 is a diagram showing a rotation speed-flow rate characteristic of a variable displacement pump of the device of the second embodiment.

FIG. 8 is a hydraulic system diagram of the third embodiment at the time of high rotation.

FIG. 9 is a sectional view showing a conventional device.

FIG. 10 is a diagram showing a rotation speed-flow rate characteristic of a variable displacement pump of a conventional device.

[Explanation of symbols]

 Reference Signs List 1 variable displacement pump 2 first orifice 4 bypass control valve 5 relief valve 11 cam ring 12 discharge port 15 displacement control valve 151 spring chamber 155 piston 157 first throttle 19 tank 41 second throttle

Claims (4)

(57) [Claims] An eccentric amount between a rotor and a cam ring is controlled in accordance with a pressure difference before and after a first orifice provided in an oil passage to a gear box to maintain a constant discharge flow rate irrespective of an increase in rotation speed. A power steering device using a variable displacement pump, wherein at the time of high rotation, the first throttle is opened via a first throttle which is opened by a relative displacement of a cam ring with respect to the rotor .
By connecting the downstream side of the orifice to the tank
A power steering apparatus using a variable displacement pump, comprising: an eccentric amount control mechanism for reducing the pressure on the downstream side of the first orifice to further reduce the eccentric amount. 2. The eccentricity control mechanism according to claim 1, wherein one end of the first eccentricity control mechanism is connected to an oil passage between the gear box and the first orifice, and the other end of the first eccentricity control mechanism is connected to an oil passage. A valve body connected to a discharge port of the variable displacement pump, a spool inserted into the valve body and mechanically connected to the cam ring, and when the spool reaches a set position, the one end communicates with a tank. A power steering device using a variable displacement pump, comprising a displacement control valve comprising a first throttle that reduces the amount of eccentricity by reducing the pressure at one end. 3. The method according to claim 2, wherein the load pressure acting on the gearbox introduced at one end, the pressure of pressure oil supplied to the other end from the first throttle of the displacement control valve, and A variable displacement pump, characterized in that a bypass control valve having a second throttle that forms an opening determined by balance with the biasing force of a second spring inserted at the other end is added. Power steering device. 4. When the load pressure acting on the gearbox introduced at one end is smaller than the biasing force of a third spring inserted at the other end, the gearbox is opened, and the capacity is increased. A power steering apparatus using a variable displacement pump, further comprising a load pressure sensitive valve having a third throttle for supplying pressure oil at one end of the control valve to the tank.